That doesn’t mean that they were infected by the fungus, said Dr. Gary Goldbaum, health officer for the Snohomish Health District.

The Everett Clinic is monitoring patients to see if any infections occurred, he said. “In fact, with months of monitoring, no patients have developed any evidence of infection,” Goldbaum said.

If patients are feeling fine, they probably don’t need to do anything, Fisk said. The fungus doesn’t usually cause infections in healthy people.

Any fungus-caused infections would most likely have occurred a week or two following exposure.

However, people with weakened immune systems, such as patients who had received a bone marrow transplant or cancer treatments, could experience a worsening of sinus symptoms, such as pain, infection and fever.

The Everett Clinic has set up a special hotline at 425-317-4609 for patients who have questions about their possible exposure. It is being staffed from 8 a.m. to 6 p.m. Monday through Friday, and from 9 a.m. until noon Saturday and Sunday.

Between March and November last year, about 2,200 patients received a treatment from ear, nose and throat specialists in which they received a mild anesthetic sprayed into their nose so that a doctor could examine and treat their sinuses.

Although the instrument that sprayed the anesthesia was sterilized with medical alcohol between each treatment as recommended by the manufacturer, sometimes fungus remained and was sprayed into a patient’s nose.

The clinic has since switched to a disposable instrument to apply the anesthetic.

“I feel they’ve taken all appropriate steps,” Goldbaum said.

State and federal public health agencies have been notified but they don’t feel an investigation is required, Goldbaum said.

The Everett Clinic periodically has found a random positive test for fungus in nose tests, Tu said. Last year, there was one positive test in March. The highest number of positive tests for the fungus, 12, came in October. There have been no positive fungus test results since Nov. 21, he said.

The Everett Clinic consulted with local and state public health officials and an expert at Stanford University on what steps to take, Tu said.

Of the 34 patients who initially tested positive for the fungus, at least five have been retested and all came back negative, he said.

“It’s incredibly unlikely that anybody will get any kind of infection from this organism,” Tu said.

Yet he said he understands that some patients may feel some anxiety when they receive a letter telling them of their potential exposure.

“We’re incredibly sorry that our patients have been exposed,” Tu said. “On the other hand, we feel it’s important to let our patients know … and for the medical community outside The Everett Clinic to understand that something like this can happen.”